bundle2: pass the operation source down to the changegroup

This is currently not used by anything in core (and redundant with the url), the
real source information is much more useful. This is going to be used in
sidedata exchange patches coming soon.

Differential Revision: https://phab.mercurial-scm.org/D9986

mercurial/bundle2.py

@@ -2001,7 +2001,7 b' def handlechangegroup(op, inpart):'
         op,
         cg,
         tr,
-        b'bundle2',
+        op.source,
         b'bundle2',
         expectedtotal=nbchangesets,
         **extrakwargs
@@ -2083,7 +2083,7 b' def handleremotechangegroup(op, inpart):'
         raise error.Abort(
             _(b'%s: not a bundle version 1.0') % util.hidepassword(raw_url)
         )
-    ret = _processchangegroup(op, cg, tr, b'bundle2', b'bundle2')
+    ret = _processchangegroup(op, cg, tr, op.source, b'bundle2')
     if op.reply is not None:
         # This is definitely not the final form of this
         # return. But one need to start somewhere.